Fig. 1. Schematic diagram of the squeeze casting process: (a) HA preform setting (preheated to 480?°C), (b) molten AZ91 pouring at 720?°C, (c) low-pressure during filtration (4-5?MPa) for 5?s and high-pressure after infiltration for 30?s, and (d) release the pressure and extraction of the ingot.

Fig. 2. Appearance of porous HA preform and AZ91/HA composite.

Fig. 3. Typical SEM micrographs of (a) porous HA perform and (b) AZ91/HA composite.

Fig. 4. SEM micrographs of (a) AZ91/HA composite, and the typical EDS spectra obtained from (b) matrix, (c) eutectic phase, and (d) porous HA.

Fig. 5. Compressive curves of the porous HA, AZ91, and AZ91/HA composite.

Fig. 6. SEM micrographs of the compressive fracture surfaces of Mg/HA composite.

Fig. 7. SEM images showing surface morphologies of the experimental samples before immersion (a) and after immersion in the SBF at 37?°C for 60?h (b), 130?h (c), and (d) 470?h.

Fig. 8. Weight evaluation of the sample after immersion in the SBF for different time periods.

Fig. 9. Schematic diagram of the ideal function process of the Mg alloy/porous HA composite in body environments at the initial (a), middle (b) and final (c) stage.